There is an increasing interest to increase the data throughput and to make more efficient use of the available spectrum in wireless data communication systems. Orthogonal Frequency Division Multiplexing (OFDM) modulation techniques with fixed cyclic prefixs are being used as one of the methods to achieve these goals. However, depending upon the application of the communication system, for example, intelligent transportation networks, maximum efficiency use of the available spectrum is certainly valued and sought after, but more importantly, the reliability on performance of the communication system/network is more valued and even imperative, when considering sustained economic success for the intelligent transportation service provider along with ensuring their consumer's safety.
The OFDM is a form of multi-carrier modulation scheme that is capable of overcoming the frequency selectivity of the radio channels and providing high data rates without an Inter-Carrier Interference (ICI) and other interferences. However, in multipath fading channels, the time variation of a fading channel over an OFDM symbol period destroys the orthogonality between the sub-channel. A circular extension, i.e., cyclic prefix, is added at the front of OFDM symbols in order to eliminate both intersymbol interference (ISI) and other interferences. For example, the cyclic prefix, which is a copy of an end of an OFDM symbol is placed at the beginning, and often used to address dispersion associated with multipath channel. The cyclic prefix, if not long enough to cover the delay spread of the wireless channel can result in having an unreliable network. However, the cyclic prefixes of each OFDM symbol, however, consume significant bandwidth and therefore reduce throughput. Also, the cyclic prefix is a predetermined and has a fixed length.
Thus, there is a need for communication systems and methods for communicating content over wireless communication networks that use cyclic prefixes to provide reliable and improved throughput.